Chain-type safety door lock



Sept. 27, 1966 B. A. QUINN 3,275,364

CHAIN-TYPE SAFETY DOOR LOCK Filed June 26, 1964 INVENTOF? 4 BERT A. Quuv/v wywjw A7- TOPNE Y5 United States Patent 3,275,364 CHAIN-TYPE SAFETY DOOR LOCK Bert A. Quinn, St. Paul, Minn., assignor to Ideal Brass Works, Incorporated, St. Paul, Minn., a corporation of Minnesota Filed June 26, 1964, Ser. No. 378,309 3 Claims. (Cl. 292-264) This invention relates generally to door locking devices, and more particularly it relates to an improved chain-type safety door lock of the type often referred to as a night latch.

Safety chain door locks or night latches of the type to which the present invention relates generally comprise a locking plate member having an elongated slot and a chain member having anchoring means at one end thereof and a coupler element at its other end for engagement within the slot of the plate member. The plate member is normally .adapted for securement on the inside surface of a door, whereas the chain member is normally anchored to an adjacent position of the door jamb, although the relative positions of the plate member and chain member may be reversed for some installations.

With chain-type safety door locks of the type noted above, intruders have devised various means for disengaging the chain coupler element from the slot of the locking plate member when standing outside of the partially opened door. By use of various means and contrivances, such as a thumb tack and rubber band for jerking the coupler element out of the slot, intruders are often able to unlatch the coupling chain even when the same has been properly installed with a minimum of working chain clearance. With this in mind, an important object of the present invention is the provision of a chain-type safety door lock which includes novel means for preventing the unauthorized disengagement of the chain coupler element from the slot by intruders standing outside of a partially opened door.

Another object of the present invention is the provision of a chain-type safety door lock which includes a strike element located adjacent the slot of the lock plate member for releasably retaining the coupler element within the slot.

Another object of the present invention is the provision of a chain-type safety door lock in which the chain coupler element is provided with spring means biasing the same into engagement with an abutment surface of the strike of the plate member so as to require the application of an inward pressure to the coupler element in order to disengage the same from the strike element before the coupler element may be released from the slot.

Another object of the present invention is the provision of a chain-type safety door lock in which the strike element of the locking plate member is designed with a cam surface sloping in a direction toward an enlarged end portion of the slot whereby the coupler element when received in the slot will ride over the cam surface and become engaged or retained by the abutment surface of the strike.

Other objects of the present invention reside in the provision of a chain-type safety door lock which effectively prevents an intruder standing outside of a partially opened door from unlocking or disengaging the latch, and which is extremely simple in construction and adaptable for economic manufacture.

The above and still further objects and advantages of the present invention will become apparent from a consideration of the following detailed specification, appended claims and drawings.

Referring to the drawings, wherein like reference Patented Sept. 27, 1966 characters indicate like parts or elements throughout the several views:

FIG. 1 is a view in perspective of a safety door lock constructed in accordance with the present invention and showing the same in a coupled or locked position;

FIG. 2 is a view in perspective of the locking plate member but showing the chain and coupler elements in an exploded perspective view; 7

FIG. 3 is an enlarged view in section taken on the line 3-3 of FIG. 1, and showing a locked or'engaged position of the coupler element by full lines, and also showing by dotted lines the position of the coupler element during initial insertive movements or final retractive movements;

FIG. 4 is a view in section corresponding to FIG. 3, but showing the position of the coupler element when inward pressure has been applied thereto for releasing the same from the strike of the plate member; and

FIG. 5 is an enlarged detail View :of the coupler element, and showing the strike of the plate member in dotted lines.

Referring more particularly to the drawings, the locking plate member is represented in its entirety by the reference numeral 1, the same comprising a generally rectangular housing 2 having a front Wall 3, opposed side walls 4, and opposed end walls 5. The rear portion of the locking plate member 1 defines oppositely extending flange portions 6 apertured to receive suitable screw fasteners 7 or the like for securely anchoring the locking plate member 1 to a door jamb, not shown. The housing 2 of the plate member 1 defines an inner chamber represented by the reference numeral 8, and the front wall 3 of the housing 2 defines an elongated slot 9 which opens into the chamber 8, as shown particularly in FIGS. 1 and 2. The elongated slot 9 defines an enlarged slot end portion 10, as is conventional.

The safety door lock provided in accordance with the present invention further comprises a chain member, represented in its entirety by the reference numeral 11. The chain member 11 includes an elongated chain 12 anchored at one end portion thereof by means of a staple ring 13 to a mounting plate 14. The mounting plate 14 is apertured and provided with suitable fasteners 15 for anchoring the same to the inside surface of a door, not shown. Although it has been noted that the plate member 1 is normally adapted for mounting on a door jamb with the mounting plate 14 of the chain member 11 anchored at an adjacent position to the door, it will be appreciated that the mounting of these elements may be reversed for convenience in some installations.

An important feature of the present invention resides in the provision of a strike 16 which projects inwardly into the chamber 8 of the locking plate'member 1. The configuration of the strike 16 is shown particularly in FIGS. 3 and 4, wherein it will be noted that the same defines a sloping or angularly extending cam surface 17 and an abutment surface 18 projecting generally perpendicularly rearwardly from the front wall 3 of the housing 2. Itwill be noted that the strike 16 is located generally adjacent the elongated slot 9 and is further arranged with the cam surface 17 thereof sloping in a direction toward the enlarged slot end portion 10 of the housing 2, as shown particularly in the drawings.

As shown particularly in FIGS. 2 and 5 of the drawings, the free end portion of the chain 12 is provided with a coupler element, represented generally by the reference numeral 19,-for reception in the enlarged slot end portion 10 of the slot 9 and slidable therealong. The coupler element 19 more specifically comprises an enlarged generally cylindrical inner head portion 20 which is of a diameter larger than the width of the slot 9 but which is also smaller than the enlarged slot end portion so as to permit the same to be inserted therewithin. The coupler element 19 further comprises an elongated stud 21 which projects generally axially from the inner head portion 20. The stud 21 is shown particularly inFIG. 2, wherein it will be noted that the stud 21 defines an enlarged shoulder 22 which is slightly smaller in diameter than the width of the slot 9. It is also noted that the axial length of the stud shoulder 22 is greater than the thickness of the housing front wall 3 (i.e., opposed walls of the slot 9), as shown particularly in FIG.3. Of course, the axial length of the stud shoulder 22must be less than the combinedthickness of the housing front wall 3 and the width of the strike '16, -so as to permit engagement of theinnerhead portion with theabutment surface 18 of the strike 16. i a

As shown in'the drawings, the stud 21: further defines a'reduced outer end portion 23,v and a washer element 24 is received thereon and normally abuts against the stud shoulder 22, as shown particularly by full lines in FIGS. 3 and 5. Of course, the washer element 24 must be of a diameter larger than the width of the slot 9. A dished spring washer 25 is carried by the reduced outer end portion 23 of the stud 21 and located adjacent the washer element 24, and the end length of the chain 12 is then placed on the reduced outer end portion 23 adjacent to the spring washer 25'. An outer washer 26 is placed on a further reduced extreme outer stud 27 (FIG. 2),

which is deformed or peened so as to rivet theouter washer 26 to the stud 21, asshown particularly in FIG. 5. With this, arrangemeng'the outerwasher 26 and riveted studouter end 27 cooperate to. define an outer head portion. 7

As shown particularly in FIGS. 3-5, the dished spring Washer 25 biases the washer, element 24 toward engagement with the stud shoulder 22. With this arrangement, the inner head portion 20 0f the coupler element 19-is movable generallyv transversely of the housing front wall 3 between inner and outer, positions, with the dished spring washer 25 normally biasing the same, toward its outer position shown by full lines in FIGS. 3 and 5.-

When the inner head portion 20 is received in the enlarged slot end portion 10 and the stud 21 of the coupler element 19 slid along the elongated slot 9, the inner head 5 portion 20 will ride over the sloping cam surface 17 of the strike 16, as shown by dotted lines in FIG. 3, and

upon a continuation of the insertive movements, the,

inner head portion 20 will snap into, engagement behind the abutment surface 18 of the strike 16, as shown by full lines in FIG. 3. This arrangement obviously prevents unauthorized disengagement of the coupler element -19 from the slot 9. When it is desired to disengage the inner head portion 20 from the abutment surface 18,

inward pressure is applied to the outer head portion or outer washer 26 of the coupler element 19 so as to move the inner head portion 20 to its inner position shown by full lines in FIG. 4, whereupon the inner head portion 20 is free to pass by the strike 16 for removal from the slot 9.

This invention has been thoroughly testedand found to be completely satisfactory for the accomplishment of c the above-noted objects; and while a preferred embodiment thereof in which the principles of the present invenlocated generally adjacent said'slot and being further arranged with the cam surface thereof sloping in a direction toward said enlarged slot end portion,

(c) a chain member having anchoring means at one end thereof and also having a coupler element at the other end t-hereof,and

(d) said coupler element being received in the enlarged end portion of said slot and slidable therealong and being outwardly biased whereby said coupled element rides over the carnsurface of-said: strike and engages, said abutment surface and .is releasably retained thereby.; Y 2. A chain-type safety door lock comprising; f (a) a locking plate member defining an inner chamber and having an elongated slot opening into said cham-' ber, said slot being enlarged atlone end portion thereof,

(b) said plate member defining a strike projectin'ginto a said chamber, said strike having a cam surface, and an abutment surface and said strike being located generally adjacent said slot and being further arranged with the cam surface thereof slopingin a direction toward said enlarged slot end portion,

(c) a chain member having anchoring means at-one said plate member between :inner and outer.

positions, 7

(5) means biasing said inner head portion toward 1 its said outer position, and (6) 'whereby upon sliding insertive movements of said coupler into said slot, the innerhead portion thereof rides over said cam surface,

and engages said abutment'surface of said strike,

said coupler inner head portion being adisengaged from said abutment surfacelupon movement of said innerhead portion to itsisaid inner position so as to permit removal of said coupler element from said slot.

3. Achain-type safety doorlock comprising:

(a) a locking plate member defining an inner chamber and having an elongated slot opening into said chamber, said .slot being enlarged at one end portion thereof, a V (b) said plate member defining a strike, projecting into said chamber, said strike having a cam surface and an abutment surface and said strike being located generally. adjacent said slot and being further ar- (c) a chain member having anchoring means at one j 7 end thereof and also having a coupler element at the other end thereof, (d) said coupler element comprising;

(1) an enlarged innerhead portion ofa diameter larger than the width of said slot but smaller,

than, said enlarged slot endportion,

(2) an elongated stud projecting from said inner,

head portion,

thickness of the opposed walls of said slot combined with the width of said strike,

(4) said inner head portion being receivable in the enlarged end portion of said slot and said stud shoulder being slidable along said slot,

(5) said stud defining a reduced outer end portion,

(6) a washer received on said reduced outer st-ud end portion, said washer being of a diameter larger than the width of said slot,

(7) an outer head portion secured to the outer end of said stud in spaced relation to said shoulder,

(8) a spring received on said reduced outer stud end portion and interposed between said washer and said outer head portion and said spring biasing said washer into engagement with said stud shoulder.

References Cited by the Examiner 5 UNITED STATES PATENTS 252,309 1/882 Goebel 292264 860,770 7/1907 Tait 292175 3,155,410 11/1964 North et a1. 292264 10 FOREIGN PATENTS 95,501 1/ 1924 Austria.

BOBBY R. GAY, Primary Examiner.

15 RICHARD E. MOORE, Examiner. 

1. A CHAIN-TYPE SAFETY DOOR LOCK COMPRISING: (A) A LOCKING PLATE MEMBER HAVING AN ELONGATED SLOT AND SAID SLOT BEING ENLARGED AT ONE END PORTION THEREOF, (B) SAID PLATE MEMBER DEFINING A STRIKE HAVING A CAM SURFACE AND AN ABUTMENT SURFACE, SAID STRIKE BEING LOCATED GENERALLY ADJACENT SAID SLOT AND BEING FURTHER ARRANGED WITH THE CAM SURFACE THEREOF SLOPING IN A DIRECTION TOWARD SAID ELONGATED SLOT END PORTION, (C) A CHAIN MEMBER HAVING ANCHORING MEANS AT ONE END THEREOF AND ALSO HAVING A COUPLER ELEMENT AT THE OTHER END THEREOF, AND 